many children with Tourette syndrome (TS) require pharmacologic therapy to alleviate their symptoms of accompanying attention- deficit hyperactivity disorder (ADHD). Although psychostimulant medications (mainly methylphenidate, dextroamphetamine, or pemoline) are usually considered the drugs of choice for ADHD, in patients with TS these medications may provoke or exacerbate tic symptoms. Hence, in order to find an alternative therapy for ADHD in TS patients, the proposed study will compare the effects of two medications, clonidine and desipramine to placebo. Both of these medications have previously been successful in treating ADHD in non-TS children. Children between the ages 7 to 13 years with TS and ADHD, who are of normal intellect and do not have psychiatric disease, will be treated in a randomized double-blind, placebo controlled protocol with each of the following: clonidine, desipramine, and placebo. Measures proposed to evaluate ADHD at the completion of each treatment period include: Child Behavior Checklists for parents and teachers; continuous performance tasks (Gordon Diagnostic System); direct-reinforcement-of latency tasks; clinical evaluation of language function (CELF); Kagen matching familiar figures tests; proteus mazes; and Barkley restricted academic setting tasks. Obsessive compulsive symptoms and the severity of motor/phonic tics will be monitored. Plasma norepinephrine and dopamine metabolites, 3-methoxy-4-hydroxyphenethyleneglycol (pMHPG) and homovanillic acid (pHVA) respectively, will be assay at the completion of each drug trail. This therapeutic study will establish the efficacy of clonidine and desipramine in children with ADHD and Tourette syndrome. The effect of tic severity and the presence of obsessive compulsive symptoms on the ability of these drugs to improve behaviors will be quantified. And finally, measurements of plasma monoamine metabolites will provide further insight into hypotheses of brain catecholaminergic system abnormalities in children with both TS and ADHD.